Changes in thymic function with age and during the treatment of HIV infection

The thymus represents the major site of the production and generation of T cells expressing alphabeta-type T-cell antigen receptors. Age-related involution may affect the ability of the thymus to reconstitute T cells expressing CD4 cell-surface antigens that are lost during HIV infection; this effect has been seen after chemotherapy and bone-marrow transplantation. Adult HIV-infected patients treated with highly active antiretroviral therapy (HAART) show a progressive increase in their number of naive CD4-positive T cells. These cells could arise through expansion of existing naive T cells in the periphery or through thymic production of new naive T cells. Here we quantify thymic output by measuring the excisional DNA products of TCR-gene rearrangement. We find that, although thymic function declines with age, substantial output is maintained into late adulthood. HIV infection leads to a decrease in thymic function that can be measured in the peripheral blood and lymphoid tissues. In adults treated with HAART, there is a rapid and sustained increase in thymic output in most subjects. These results indicate that the adult thymus can contribute to immune reconstitution following HAART.     

GI tract unraveling with curved cross sections

Gastrointestinal (GI) tract examination with spiral/helical computed tomography (CT) is currently performed by slice-based inspection of axial images. CT colography is a recent advance which allows an intraluminal visualization of the colon, similar to endoscopy. Various rendering algorithms have been developed with promising results, however navigation through the complex, tortuous anatomy of the colon can be time consuming in practice. In this paper, the authors propose an electrical-field-based method to unravel the convoluted colon, that is, to digitally straighten it with curved cross sections and flatten it over a plane. In the authors' method, electrical charges are simulated along the central colon path. Curved cross sections are defined by the electrical force lines, and lead to consistent unraveling. It is demonstrated with image volumes of two patients that this technique produces a global planar view of complicated colon features with a potential for detection of polyps     

Ergonomics around the world-The United States of America

The history and development of human factors engineering, or ergonomics, and of the Human Factors Society, is traced for the American scene. Selected problems of current interest are given from the fields of aviation, highway safety, architectural design, environmental control, and consumer products. In conclusion, the more significant areas which might occupy specialists in this field during the next decade are emphasized.     

Controlled trials of CQI and academic detailing to implement a clinical practice guideline for depression

BACKGROUND: The release of the Agency for Health Care Policy and Research (AHCPR)'s Guideline for the Detection and Treatment of Depression in Primary Care created an opportunity to evaluate under naturalistic conditions the effectiveness of two clinical practice guideline implementation methods: continuous quality improvement (CQI) and academic detailing. A study conducted in 1993-1994 at Kaiser Permanente Northwest Division, a large, not-for-profit prepaid group practice (group-model) HMO, tested the hypotheses that each method would increase the number of members receiving depression treatment and would relieve depressive symptoms. METHODS: Two trials were conducted simultaneously among adult primary care physicians, physician assistants, and nurse practitioners, using the same guideline document, measurement methods, and one-year follow-up period. The academic detailing trial was randomized at the clinician level. CQI was assigned to one of the setting's two geographic areas. To account for intraclinician correlation, both trials were evaluated using generalized equations analysis. RESULTS: Most of the CQI team's recommendations were not implemented. Academic detailing increased treatment rates, but--in a cohort of patients with probable chronic depressive disorder--it failed to improve symptoms and reduced measures of overall functional status. CONCLUSIONS: New organizational structures may be necessary before CQI teams and academic detailing can substantially change complex processes such as the primary care of depression. New research and treatment guidelines are needed to improve the management of persons with chronic or recurring major depressive disorder.     

Characterization of infrared absorption by powder coatings on steel panels

Interest in faster curing systems has led to infrared (IR) curing of powder coatings. The efficiency of IR heating depends on both the coating spectral absorption characteristics and the spectral emissions of the infrared source. Coating spectral absorptivities were measured with an FTIR spectrometer with an integrating sphere. Using the spectral absorptivities and normalized blackbody emissions, integrated average absorptivities and overall radiant efficiencies were calculated for blackbody emitter temperatures ranging from 500 to 3000 K (440 to 4940°F). The effects of several powder coating parameters on spectral absorptivities, integrated average absorptivities, and overall radiant efficiencies were studied. School of Textile & Fiber Engineering, Atlanta, GA 30332-0295. 1079 West Nancy Creek Dr., Atlanta, GA 30319.     

Surface characteristics generated in CNC chip breaking tool paths

One method for creating broken chips in turning processes involves oscillating the cutting tool in the feed direction utilizing the CNC machine axes. Using computer simulations it is possible to combine the motion of the axes with the geometry of the cutting tool to predict the surface characteristics, mapping surface parameters for a wide range of chip breaking situations. These data allow the selection of chip breaking cutting parameters to simultaneously ensure broken chips, and acceptable surface characteristics. This paper describes the computational method, and presents results of comparison for cutting tests using single axis, linear taper and outer contouring motions.